Effect of Attaching Gas Addition on Plasma Parameters in Inductive Ar/O2 and Ar/CF4 Discharges

Abstract

Electron energy probability functions (EEPFs) are measured with a Langmuir probe in inductively coupled RF (13.56 MHz) Ar/O2 and Ar/CF4 discharges at 15, 30 and 50 mTorr of the total pressures by changing the attaching gas content from 0 to 30%. The bulk of the measured EEPFs is approximately Maxwellian, although there is a slight depletion from a Maxwellian distribution in the high-energy region. The electron density markedly decreases in the attaching gas content below 5–10%, beyond which it remains nearly constant. On the other hand, the electron temperature increases gradually with increasing attaching gas content. A global model for electronegative plasma is used to study the effect of attaching gas addition to Ar discharges on the plasma parameters assuming the Maxwellian electron energy distribution. The model results are compared with the experimental results, obtaining reasonably good agreement.